1. Field of the Invention
The present invention relates to a scroll fluid apparatus which may be employed for use in an air compressor, a vacuum pump, for example. More particularly, the present invention relates to a scroll fluid apparatus that is provided with an auxiliary crank as a rotation prevention mechanism.
2. Description of Prior Art
A typical known scroll fluid apparatus has a driving shaft that has a crank portion, a revolving scroll that is connected to the crank portion to revolve in response to the rotation of the driving shaft, and a fixed scroll that cooperates with the revolving scroll to compress a fluid. The temperature of the revolving scroll is raised by heat generated when it compresses the fluid, and by heat generated from a bearing portion disposed between the revolving scroll and the crank portion. Since the revolving scroll is connected to auxiliary cranks such that it revolves without rotating around its own axis, the revolving scroll inevitably has a large thickness, so that when it is heated, its temperature does not rise uniformly, resulting in a warping of the revolving scroll. In addition, since the allowable change in position of the auxiliary cranks is not large, a large force is applied to the auxiliary cranks by the thermal expansion of the revolving scroll, which may give rise to problems such as breakage. The revolving and fixed scrolls each have an end plate one face of which is mirror-finished. Thus, deformation of the end plate is a serious problem.